Finding the Third Proportional to 9,978 and 21,291

Step by Step Solution

1. Step 1: Write the proportion equation
   9,978 : 21,291 = 21,291 : x
2. Step 2: Convert to fraction form
   9,978/21,291 = 21,291/x
3. Step 3: Cross multiply
   9,978x = 21,291 × 21,291
4. Step 4: Simplify right side
   9,978x = 453,306,681
5. Step 5: Solve for x
   x = 453,306,681/9,978
6. Step 6: Final answer
   x = 45,430.62